Abstract

OBJECTIVE: To determine if patients treated with extracorporeal shockwave lithotripsy (ESWL) are at a greater risk of developing diabetes mellitus (DM) than those treated with ureteroscopy (URS). PATIENTS AND METHODS: A retrospective population-based cohort study was performed of all ESWL and URS stone treatments done in Ontario between January 1994 and March 2014, utilising linked encoded healthcare databases. The primary outcome was the development of DM >90 days after treatment. The Kaplan-Meier method was used for unadjusted survival analysis and multivariable analysis with Cox proportional hazards regression was used to assess the risk of DM between the ESWL and URS groups whilst controlling for age, gender, region of residence, income quintile, year of treatment, and comorbidity index. A sensitivity analysis with a subset of ESWL patients treated for left renal or proximal ureteric stones was completed. RESULTS: We identified 106 963 patients who underwent ESWL or URS over the study period with a median follow-up of 6.6 years (ESWL 8.5 years, URS 5.6 years). Unadjusted survival analysis showed an increased risk of developing DM in the ESWL group compared to the URS group (P < 0.001); however, multivariable analysis showed no increased risk of DM in the ESWL cohort (hazard ratio [HR] 0.97, 95% confidence interval [CI] 0.91-1.02; P = 0.25). Similarly, sensitivity analysis showed no increased risk of DM in the left renal/proximal ureteric stone ESWL cohort compared to the URS cohort (HR 1.04, 95% CI 0.96-1.13; P = 0.35). CONCLUSIONS: Our population-based cohort study demonstrated no increased risk of DM in patients undergoing ESWL compared to URS.

Comments
1

The possibility that SWL might cause development of DM has remained an important concern over time and different results have been reported in the literature.

In the present large population-based comparison of patients treated with either SWL or URS, the conclusion was that there was no increased risk of DM following SWL.

The advantages of this report is the large number of patients; 48 351 in the SWL-group and 58 612 in the URS-group. Stratification of the location to which shock waves were directed was a further advantage. Moreover, and slightly surprising, was the fact that most patients (57%) had been treated with SWL twice and as many as 38% with more than three sessions! Despite this no increased risk of DM was demonstrated.

Given the large populations and long term follow-up not only of SWL-treated patients, but also of the large and well controlled group of URS-treated patients for comparison, the findings are of great clinical importance.

It is of note, however, that during a follow-up of ~18 years only approximately 38% of the stone patients remained free from DM and after 5 years about 5%. These observations show the close association between stone disease and DM, something that always should be kept in mind when studies on the possible development of DM are carried out.

The possibility that SWL might cause development of DM has remained an important concern over time and different results have been reported in the literature.
In the present large population-based comparison of patients treated with either SWL or URS, the conclusion was that there was no increased risk of DM following SWL.
The advantages of this report is the large number of patients; 48 351 in the SWL-group and 58 612 in the URS-group. Stratification of the location to which shock waves were directed was a further advantage. Moreover, and slightly surprising, was the fact that most patients (57%) had been treated with SWL twice and as many as 38% with more than three sessions! Despite this no increased risk of DM was demonstrated.
Given the large populations and long term follow-up not only of SWL-treated patients, but also of the large and well controlled group of URS-treated patients for comparison, the findings are of great clinical importance.
It is of note, however, that during a follow-up of ~18 years only approximately 38% of the stone patients remained free from DM and after 5 years about 5%. These observations show the close association between stone disease and DM, something that always should be kept in mind when studies on the possible development of DM are carried out.